Several detractors — who didn't appear to be fans of the Joe Biden presidency to begin with — accused the First Lady of looking "trashy" in the tights.
Another tweeted that Dr Biden looked like "Madonna's grandmother" and was "too old" to be wearing an outfit like that.
"They might be expensive but she looks trashy as heck dressed like that. What an embarrassment of 1st lady," one person tweeted.
But there were more people defending her outfit and comparing the flap to other overblown White House fashion moments.
"Jill Biden's fishnet stockings, Barack Obama's tan suit, Michelle Obama's sleeveless dress. Yes, these are the biggest scandals in American politic," one person tweeted.
"Apparently people are mad that Jill Biden wore 'fishnets'. These are not even fishnets, people. They're just patterned tights," another person wrote.
Dr Biden is the first wife of a US President to work full-time while in the White House. She holds a doctorate in education and is a professor of English.
First ladies and fashion
US First Ladies have long faced scrutiny and often criticism for their outfit choices.
Michelle Obama was famous for wearing sleeveless dresses that showed off her toned arms, but some detractors labelled them too informal and inappropriate during the cooler months.
Meanwhile, during Donald Trump's presidency, Melania Trump's outfits were frequently the source of attention.
During the 2016 election, following the release of the infamous "grab them by the pussy" tape, Melania wore a blouse featuring a pussy-bow neckline to her next public event.
She also stoked anger with her "I don't really care, do u?" jacket, which she wore during a visit to a migrant child detention centre in 2018.
After being accused of using it sending a message on migration, Melania Trump came out and clarified that the jacket had been a message not directed to those in detention, but to the "people and for the left-wing media who are criticising me".
